Chitosan‐Ethylenediaminetetraacetic acid‐palladium composite for the Suzuki–Miyaura reaction

Palladium catalyst supported on chitosan‐EDTA composite, CS‐EDTA‐Pd, was prepared by a simple dissolution method. The chitosan and EDTA (1:1.5 by wt.) were dissolved in dilute acetic acid, then formed the beads, which were used to adsorb palladium(II) and finally reduced to palladium(0) by refluxing in ethanol. The as‐prepared CS‐EDTA‐Pd was characterized by Fourier transform infrared (FT‐IR) spectroscopy, scanning electron microscopy (SEM), energy dispersive X‐ray spectrometry (EDX), and X‐ray photoelectron spectroscopy (XPS). Then catalytic activities of the CS‐EDTA‐Pd catalyst were tested in the synthesis of biaryls from aryl halides and phenylboronic acid using the Suzuki–Miyaura cross‐coupling reaction. The results have shown that the CS‐EDTA‐Pd was successfully applied as a catalyst for the Suzuki–Miyaura to couple aryl iodide and aryl bromide substrates under mild reaction conditions using ethanol as solvent and potassium carbonate as a base. The reactions at 80°C for 2 h under a normal atmosphere results in biaryls at good to excellent yields (>90%). This catalyst is inexpensive, simple to prepare, easy to separate from the reaction by filtration, and can be reused for five consecutive runs with a slight loss of product yields.